Patent Literature 1 discloses a fail-safe technique used in large-sized liquid crystal display devices in which a display unit is divided such that the display unit is controlled by a plurality of controllers. In this technique, link signals are transmitted bidirectionally between each controller that controls a portion of the display unit and the other controllers that control the other portions of the display unit so that when there is a malfunction in one of the areas of the display unit, all the other areas are immediately controlled to display a black screen.